The background description provided herein is for the purpose of generally presenting the context of the disclosure.
Diesel engines combust diesel fuel in the presence of air to produce power. The combustion of diesel fuel produces exhaust gas that contains particulate matter. The particulate matter may be filtered from the exhaust gas using a diesel particulate filter (DPF). Over time, the particulate matter may accumulate within the DPF and may restrict the flow of exhaust gas through the DPF. Particulate matter that has collected within the DPF may be removed by a process referred to as regeneration. During regeneration, particulate matter within the DPF may be combusted.
Regeneration may be accomplished, for example, by injecting fuel into the flow of exhaust gas upstream of the DPF. One or more catalysts also may be disposed in the stream of exhaust gas and may combust the injected fuel. The combustion of the injected fuel by the catalysts generates heat, thereby increasing the temperature of the exhaust gas. The increased temperature of the exhaust gas may cause particulate matter accumulated within the DPF to combust.
The exhaust gas produced by diesel engines also contains gaseous compounds, such as nitrogen oxide (NOx), and may be treated to reduce the emission of the gaseous compounds. For example, a selective catalytic reduction (SCR) system, which injects an ammonia compound into the exhaust gas, may be used to reduce the emission of NOx compounds.